Treatment with 2CDA that interferes with the generation and/or survival of lymphocytes and monocytes may have a beneficial effect in psoriatic synovitis and skin lesions by hindering cell recruitment and function in sites of inflammation. The prolonged decrease in T-lymphocytes after 2CDA treatment should prevent new lesion formation, limit progression of immune-mediated process in joints and skin and cause regression of arthritis and/or prevent new joints from becoming infected.